同向运动红外光度密度：0<z<1范围内冷星系的主导作用
The Comoving Infrared Luminosity Density: Domination of Cold Galaxies across 0<z<1
摘要：
在本文中，我们研究了不同的红外（IR）光谱能量分布（SED）的星系的贡献的同向红外光度密度，代理同向恒星形成率（SFR）密度。我们将星系划分为冷或热的红外SED，这取决于它们的峰值红外能量输出的静止帧波长是高于还是低于90 μ m。我们的工作是基于本地宇宙和高红移的远红外选择样本，前者由IRAS 60 μ m选择的z<0.07的星系组成，后者由Spitzer 70 μ m选择的0.1<z<1的星系组成。我们发现，每个红移/光度箱的总红外光度密度与其他深中/远红外调查的结果吻合得很好。在z<0.07时，我们观察到了先前已知的结果：中等光度星系（L_IR<10^11 Lsun）在总光度密度中占主导地位，冷星系的比例随着光度的增加而减少，在最高光度时可以忽略不计。相反，当z=0.1以上时，我们发现红外发光星系（L_IR>10^11 Lsun），其中大部分是冷星系，在红外光度密度中占主导地位。因此，我们推断冷星系在整个0<z<1范围内主导红外光度密度，因此似乎是SFR密度增加到z~1的主要驱动力，而本地发光星系总体上并不代表高红移人口。
英文摘要：
In this paper we examine the contribution of galaxies with different infrared (IR) spectral energy distributions (SEDs) to the comoving infrared luminosity density, a proxy for the comoving star formation rate (SFR) density. We characterise galaxies as having either a cold or hot IR SED depending upon whether the rest-frame wavelength of their peak IR energy output is above or below 90um. Our work is based on a far-IR selected sample both in the local Universe and at high redshift, the former consisting of IRAS 60um-selected galaxies at z<0.07 and the latter of Spitzer 70um selected galaxies across 0.1<z<1. We find that the total IR luminosity densities for each redshift/luminosity bin agree well with results derived from other deep mid/far-IR surveys. At z<0.07 we observe the previously known results: that moderate luminosity galaxies (L_IR<10^11 Lsun) dominate the total luminosity density and that the fraction of cold galaxies decreases with increasing luminosity, becoming negligible at the highest luminosities. Conversely, above z=0.1 we find that luminous IR galaxies (L_IR>10^11 Lsun), the majority of which are cold, dominate the IR luminosity density. We therefore infer that cold galaxies dominate the IR luminosity density across the whole 0<z<1 range, hence appear to be the main driver behind the increase in SFR density up to z~1 whereas local luminous galaxies are not, on the whole, representative of the high redshift population.
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